ScienceShot

A hydrogen generator that runs on an ordinary AAA battery

Hydrogen is just about the cleanest fuel you can imagine: The only exhaust it produces is water. A simple way to produce hydrogen is electrolysis, which uses electric current to split hydrogen and oxygen atoms in water molecules apart. To do that, researchers stick two metal plates connected to a power source into pure water. When electricity passes through the plates, called electrodes, hydrogen appears at the cathode and oxygen at the anode. Until now, scientists have had to use precious metals like platinum for the electrodes, because these metals conduct electricity efficiently and do not decay easily in water. But the prohibitive cost of such metals limits the technology’s application in large-scale industrial processes. Now, a team has found a cheaper alternative: nickel metal coated with nickel oxide and attached to carbon nanotubes. Using the nickel electrodes, the team made a water splitter that runs on an ordinary 1.5-volt battery, as shown in the picture above. As of now, the electrodes lasts only days in water, but the researchers hope to improve the material—described today in Nature Materials—so it would last weeks or months—and save hydrogen producers billions of dollars.